Reasoning behind changes:

Just a couple of ideas, jotted down, so you guys can get a feel for why I made the changes.

The intent of this mod is to improve the depth of effective tactics and increased the difficulty. Would you like to engage in long range duelling or sniping, how about scouting with your F.O. for strike packages or using high evasion tactics to out flank, its all possible now.  Tweaks to evasion, sensors, visual range, height advantage, range splits, morale, weapon ranges, initiative, weapon stats, skills and more. Save game compatible.
Now don't get me wrong, the vanilla game is a fun way to play and those medium range slugfest's are brilliant, I love metal meat suit jousting, but after a few hours I was after something a little different that allowed me to change my tactics and effectively use a PPC, AC5, Large Laser or dare I say it AC2.  I will be nostalgic (and heavily subjective) but I loved the long range battles on the board game, and I feel this game doesn't replicate them very well.

These changes have done little to dampen the effectiveness of a medium range brawl, its still fun and visceral and a good solid tactical option.  It would be remiss of me to discourage medium range engagements, as the idea behind this mod is to add more tactical depth not remove any.  I want this mod to give options to effectively explore tactics, without that feeling of "I'm doing it wrong".

Long Ranged Weapons(PPC, LRM, AC, LL) have had their ranges increased to give more time at long range combat and the flexibility to remain at long range, if your good enough. This adds more flexibility into tactics and with the increased difficulty, penalizes poor positioning and decision making.  The AI doesn't just bum rush anymore (although it seems to prefer that tactic) with this mod you have to deal with high evasive targets, positioning, maneuvering, and flanking elements .  The surprising thing is the AI is not to bad at capitalizing on this, and its been fun long range duelling with the AI.  This does make it a touch harder to get into brawling range, but with use of terrain the difficulty is minor.

The difficulty to hit at long range can seem somewhat extreme if you don't adjust your playstyle and loadout.  For example; If you only have 1 long range weapon on each mech you may find the engagements lack luster, because you can't bring to bare enough firepower to get through the defenses.  Another example; LRM5s are now a very useful addition to a Mechs in the hands of a pilot that has Multi Target Skill, while engaging one target they can strip a pip of evasion off of another, do this with 3 mechs remove 6 difficulty to hit off a primary target for your heavy hitter. sensor lock(now called Targeting Lock) can be quite effective as well, stripping 3 charges of  evasion and removing guard, great on a short range brawler unable to engage at long range.

Medium Range weapons have there max range increase by 30 (1 hex), and long range stops at 270 with the exception of the AC20, which has been given 1 more hex.  This was made to add a little bit of love back to medium range, its balanced with a higher difficulty in the max range bracket.  The minimum range difficulty has been increased by 2 to counter the effectiveness of weapons that are suppose to be terrible under minimum range.

Movement to hit penalty added to give some love back to Guard, since it can be stripped now by Targeting Lock. 

Visibility
This was a pain to sort out and quite a let down.  There is little difference between spotting distance and sensor range.  Unfortunately the term spotting distance is counter intuitive, while it may appear to just be visual range,  it also performs a similar function to sensor range.  In that Mech & Vehicle locations will be revealed within spotting distance range regardless of LOS visibility, but they will only be shown as "unknown" Mech & Vehicle until you have LOS on them.  As opposed to sensor range, which will also reveal Mech & Vehicle locations but with a little more detail (Blips, Unknown, Semi Data) , sensor range also governs the range of sensor lock, but it won't provide visual acquisition.  There is also a noticeable lag when setting the spotting distance to very high levels.
I tried to do something fancy by making spotting range larger than visual range, allowing you a great LOS but if a mech remains hidden you have to wait till you pick it up on sensors (awesome for scouts).  Works kind of ok in PVP, but the AI is quite dumb, I found it would just sit there and take damage if you have entered visual range and not sensor range.  

The spotter tactics multiplier seems to do nothing, I have played with lots of values and non seem to have any effect.  Same for Sensor Hysteresis  Additive, which I thought would be an awesome addition but I couldn't get it to do anything.  

Morale
I wanted to make morale less bursty and more steady as long as your shooting, it works fairly well given that cost changes.

Missile Systems
Clustering reduced by 50%, LRM minimum range increased, minimum range difficulty increased provides a balance for LRMs, that's not just a straight damage or stability damage reduction.  I had reduced stab damage at first, but then that took a lot of the fun away from LRMs, they just weren't as rewarding to shoot, and with the evasive changes it was to big a nerf.  SRM's had there damage slightly reduced because of how hard they hit, but to compensate they have had an accuracy boost

Lasers
Lasers have been given a larger medium range bracket, cutting back a little on the long range bracket. Particularly Medium Lasers, with the introduction of the extra range brackets I wanted to give some advantage back to Medium lasers, by shortening their long range difficulty.  Additionally I have added a little bit of diversity to Laser variants just for some spice and to see how the idea plays out, if it works then I may add a little bit more diversity to other weapon systems, depending on feedback.  

Autocannons
As much as I have tried to make Autocannons worth their tonnage it was a struggle. On paper it is hard to justify the large tonnage for an AC, given that with some simple heat management, SRMs, LRMs, Lasers and PPCs (in this mod) easily out perform on a tonne for tonne basis.  Stability has been drastically increased, so Autocannons along with LRMs are now your go too knock down and debuff weapons, giving them a clear tactical use and worth the tonnage.  Autocannons also have great  range brackets and set the standards range splits across all weapon systems.  AC minimum range has been removed, this is to add more value to the weapon systems and well it is a kinetic weapon after all! With the exception for AC2, because of its massive range. Autocannons were also given a debuff skill, this makes them competitive with PPCs, which have  much improved heat, damage and range.

Particle Projection Cannons
The PPC weapon system was under performing, heat was to high for damage output.  Ton for Ton the AC10 was a far superior weapon, even with the 5% accuracy debuff to target from a PPC. Additionally the weapon system was simply nonviable at medium range compared to the medium lasers and SRMs.  Minimum range penalty has been increased making the PPC quite ineffective at close quarters, debuff has been increased by lasting 2 rounds and stacking up to 2 times.